Rhinoceros poaching has exploded in recent years, all due to a booming market for their horns, which traditionally are believed throughout Asia (particularly in Vietnam) to hold medicinal properties. The horns are widely thought to be an aphrodisiac, a cure for convulsions and even a treatment for hangovers. Of course, there is no scientific evidence to support such beliefs, but demand for rhino horns continues to grow. Depressingly, 2012 set a record for rhino poaching in South Africa, with 668 rhinos killed in that country alone. (Guardian U.K.)